Most doctors know essentially nothing about nutrition. They get about two hours' lectures on it during an entire medical degree course. And only specialists will know anything about food intolerance and special dieta. Try finding one.

Dietitians are not much better. The standard text, by Bryony Thomas, used to cover diets for specific medical conditions but eliminated all that in the current edition. It seems to be intended to teach people how not starve patients in hospitals and nursing homes, and no more than that.

"See your doctor" isn't a lot of help.